Non-Causal (due to confounding)
Characteristic Under Study
Factor X Disease Disease
Interpreting Associations- Causal and Non-Causal
Causal Coffee Consumption
终止效应
剂量反映关系 关联的特异性
关联的生物学合理性
因果推断标准(1)--关联的强度
criteria of causal inference 1--strength
☻关联强度越大，为因果的可能性越大
inference of causal association
Environmental Exposure or Genetic Background or Combination of Both
Association
? Causation ? Disease or Other Outcome
Suppose we determine that an exposure is associated with disease. How do we know if the observed association reflects a causal relationship?
Non-Causal (due to confounding) Coffee Consumption
Real Association
Spurious
Association
Smoking
Real Association
Pancreatic Cancer
Pancreatic Cancer
统计关联到因果关联
三角模型（epidemiological triad）
环境 Environment
Model of Disease
病因 Agent
宿主 Host
三角模型（epidemiological triad）
宿主 宿主
失衡
病因
环境
病因
环境
健 康（health）
疾 病（disease）
三角模型（epidemiological triad）
一、因果推断的一般过程
Common process of causal inference
建立病因假设
hypothesis development
病因假设的检验和验证
test and certification of hypothesis
建立病因假设（ hypothesis development ）
关联的强度 关联的重复性 关联的时间顺序 病因与疾病分布一致
strength
consistency
temporality coherence reversibility dose-response relationship specificity biologic plausibility
From Epidemiological Association to Causation
暴露与疾病
exposure and diassociation
有无偏倚?
bias
有时间先后否?
temporal sequence
第三节 病因推断标准
criteria of causal inference
Genetic Codes
Social / Psychological Environment
Physical Environment
轮状模型（wheel model）
社会环境
生物环境
社会环境
生物环境
遗传内核
遗传内核
失衡
宿主
理化环境
宿主
理化环境
健康 Health
疾 病 Disease
生物环境 社会环境 理化环境
遗传内核 宿 主
健 康 Health 先天性代谢异常
Inborn error of metabolism
生物环境
社会环境
理化环境
遗传内核
宿 主
健 康 Health
麻疹 Measles
病因网络模型（web of causation）
Morbidity and Mortality (Stroke, MI) Biological Risk Factors (Hypertension, Blood Lipids, Homocysteine)
Genetic Risk Factors (Family History) Behavioral Risk Factors (Cigarette, Diet, Exercise)
Environmental Factors (Socioeconomic Status, Work Environment)
Agent Host
环境
Environmental
三角模型（epidemiological triad）
Host Agent
环境
Environmental
三角模型（epidemiological triad）
Agent Host
环境
Environmental
三角模型（epidemiological triad）
因果关联的推断（inference of causal association）
病因推断的标准 (criteria of causal inference )
第一节 病因的概念 concepts of causation
一、疾病病因概念的发展
（ Development of causation in history ）
high.
钩端螺旋体病流行，共同点---下水劳动
差异法（different canon）
The frequency of a disease occurrence is extremely different under different situations or conditions. If a risk factor or event can be identified in one condition and not in a second, it may be that factor, or the absence of it, that may be the cause of the disease.
病因和病因推断
Cause of Disease and Causal Inference
流行病学教研室
Department of epidemiology ，Harbin Medical University
主要内容 (outline)
病因的概念 （concepts of causation）
察布查尔病
共变法（concomitant variations canon）
The frequency or strength of an event or risk factor
varies with the frequency of the disease or condition.
Increased numbers of children not immunized against measles causes the incidence rate for measles to go up.
求同法（agreement canon）
If events or risk factors are common to a variety of different circumstances and the events or risk factors have been positively associated with a disease, then the probability of that factor being the cause is extremely
约翰.霍普金斯大学流行病学教授
二、病因的定义（definition of causation）
那些能使人群发病概率升高
的因素，就可认为是疾病的
病因；当其中某个或多个因
素不存在时，人群的疾病频
率就会下降。
Lilienfeld AM.（1920-1984）
约翰.霍普金斯大学流行病学教授
第二节 因果关联的推断
密尔氏准则
Mill’s canons
密尔氏准则（Mill’s canon)
求同法 （Method of agreement）
差异法 （Method of difference）
共变法 （Method of concomitant variation）
剩余法 （Method of exclusion）
病因网络模型（web of causation）
BEINGS Model Preventable causes of disease
Biologic factors and Behavioral factors
Environmental factors
Immunologic factors Nutritional factors Genetic factors Services, Social factors, and Spiritual factors
Host Agent
环境
Environmental
三角模型（epidemiological triad）
Agent Host
环境
Environmental
轮状模型（wheel model）
Chemical Environment Human Organism